Neurogenesis and Alzheimer's disease: Biology and pathophysiology in mice and men.

The hippocampus is critical for learning and memory and heavily affected in dementia. The presence of stem cells in this structure has led to an increased interest in the phenomenon of adult neurogenesis and its role in hippocampal functioning. Not surprising, investigators of Alzheimer's disease have also evaluated adult neurogenesis due to its responsiveness to hippocampal damage. Although causal relationships have not been established, many factors known to impact neurogenesis in the hippocampus, are implicated in the pathogenesis of AD. Also, adult neurogenesis has been proposed to reflect a "neurogenic reserve" that may determine vulnerability to hippocampal dysfunction and neurodegeneration. Since neurogenesis is modifiable, stimulation of this process, or the potential use of stem cells, recruited endogenously or implanted by transplantation, has been speculated as a possible treatment of neurodegenerative disorders. As the structural and molecular mechanisms governing adult neurogenesis are important for evaluating therapeutic strategies, we will here review collective literature findings and speculate about the future of this field with a focus on findings from Alzheimer's mouse models. Continued research in this area and use of these models is critical for evaluating if neurogenesis based therapeutic strategies will indeed have the potential to aid those with degenerative conditions.